From a strategy gamers point of view, Starcraft by faaaar. I don't know much about the story and lore of either game, don't really light up my interest. SC2 is nice balance between these two games, I think.

Anyone who plays Starcraft online anymore are just Koreans who are so good at the game they will win every time. The custom maps are clever most of the time, but are useally hacked and look really bad. 2D Graphics can give you a headache after a while.